Vehicle brake lining wear indicator



April 21, 1953 E. A. BRANSCHOFSKY 2,636,090

VEHICLE BRAKE LINING WEAR INDICATOR Filed July 13, 1950 IN VEN TOR.600/020 4. BM VSCHOFSKY,

WW 'm ATTQRNEYS Patented Apr. 21, 1953 UNITED STATES PATENT OFFICEVEHICLE BRAKE LINING WEAR INDICATOR Edward A. Branschofsky, Detroit,Mich. Application July 13, 1950, Serial No. 173,667

1 Claim.

This invention relates to a brake lining wear indicator, and moreparticularly to a safety signal device associated with the brake shoe ofa vehicle for giving an audible or visual signal to the driver when thebrake linings are substantially worn out to thereby indicate the needfor replacement to prevent scoring of the brake drums.

It is the object of the present invention to provide a safety signaldevice associated with the vehicle brake and which is substantiallysimple in construction to provide a positive indicator when the brakelinings have worn to the danger point or where the wear is such thatfurther use will result in scoring of the brake drums.

This and other objects will be seen from the following specification andclaim in conjunction with the appended drawing in which- Fig. 1 is aside elevational view partially in section illustrating the relationshipof the brake shoe, lining and drum and the brake lining wear signaldevice mounted upon the said brake shoe; and

Fig. 2 is a section on line 2-2 of Fig. 1.

It will be understood that the above drawing illustrates merely apreferred embodiment of the invention and that other embodiments arecontemplated within the scope of the claim hereafter set out.

Referring to the drawing the vehicle brake assembly includes the wheelelement II which has secured thereto upon opposite sides the arcuatebrake drums I 2. The brake shoes I3 with pivotal mountings I4 at theirlower ends are interconnected adjacent their upper ends by the coilspring I5. Rotatable disc I 6 with actuating lever I1 joined thereto isconnected to the upper ends of the brake shoes I3 by the links 18 whichare respectively joined pivotally at l9 to opposite sides of operatingdisc I6 and pivotally joined to the upper ends of the brake shoes I3 bythe pivotal connections 20.

A pair of arcuate brake linings 2i are suitably secured or bonded to thearcuate flanges 2| of brake shoes I3 and are adapted upon application ofthe vehicle brakes for movement towards and frictional engagement withthe interior arcuate surfaces 22 of the rotatable brake drums I2.

The brake lining wear indicating device includes the plastic ornon-metallic housing 23 which is secured to the outer wall of brake shoeI3 by the strap 24 and the attaching screws 25 as shown in the drawing.Housing 23 has an elongated bore 26 which terminates in the bore 21 ofincreased diameter and the rod or shaft 28 extends through said bores.

The piston 29 upon the outer end of the rod 28 is positioned within theenlarged bore 21 in housing 23 and extends partially into thecounterbore 3| upon the inner surface of lining 2I ad- Jacent to thebore 21.

The outer end of housing 23 has a circular shoulder 30 of reduceddiameter which is positioned through the corresponding transverseopening in the wall of the lining mounting flange 2| there being asuitable, preferably rubber, washer 36 interposed between housing 23 andthe inner surface of the flange 2 I as shown in Fig. 1.

Coiled spring 32 is positioned within the enlarged bore 21 and aroundthe rod 28 with the outer end of said spring bearing against the piston29 tending to urge the same outwardly of said housing.

Ground wire connector 33 over the outer projecting threaded end of rod28 there being a rubber washer 35 and a fiber Washer 34 positioned uponsaid rod and interposed between wire connector 33 and housing 23.

The ground wire 31 is joined at its lower end to wire connector 33 asshown in Fig. 1 and the upper end thereof extends to one of theterminals of the light signal or bulb 38 which is positioned within asuitable socket within the vehicle dash 39. Electrical energy isdelivered to the other terminal of bulb 38 by the single wire 42 whichinterconnects said terminal with the electrically energized side of thevehicle ignition switch 4I positioned within the dash 39 which extendsfrom and is joined to the vehicle frame 40.

is threadably secured a Under normal operation the bulb 38 is not en-'ergized for the reason that the ground wire 31 is not effectivelygrounded to the vehicle body, being normally spaced from the metallicdrum I 2. However after there has been considerable wear of the brakelining 2I to the point where said linings should be replaced, it will beapparent from Fig. 1 of the drawing, that the outer end of piston 29will be exposed, and upon outward movement of the brake shoe I3 uponapplication of the brakes, said rod 29 will come into physical contactwith the inner surface 22 of said drum. Thus the electrical circuitthrough the signal device 38 will be completed and at that moment thebulb 38 will be energized.

This will indicate the condition of the brake linings 2I which if thenreplaced will prevent future scoring of the interior surface 22 of thebrake drums I2. In the present embodiment a light bulb 38 is shown forillustration however it is contemplated that an audible signal such as abuzzer could be substituted therefor. In any event the present mechanismprovides a prac- 3 tical device to indicate that it is time to replacebrake linings 2|.

While I have shown in Fig. 1 a rotatable disc l6 actuated by a lever I!for expanding the brake shoes l3, it is naturally contemplated that anyother suitable conventional or hydraulic mechanism may be employed forso expanding said brake shoes. I I II I I While the present constructionhas been directed tovehicle brake linings, it is naturally contemplatedthat the present lining wear indicating device may be used in any otherindustrial construction or equipment which requires the use of brakelinings.

Having described my invention" reference should now be had to the claim,which follows for determining the scope thereof.

I claim:

A brake shoe lining weai switching means coma vehicle brake drum,

I a non-metallic housing secured to said shoe and having a longitudinalbore therethrough with the outer portion thereof of increased diameter,s ai d lining having a counterbore in its inner surface adjacent theprising in combination II I a movable shoe, a lining thereon,

4 enlarged bore of said housing, a rod slidably extending through thebore of said housing, a piston on said rod positioned within saidenlarged bore and extending partially into said counterbore, a coiledspring within said enlarged bore and bearing against said pistonnormally urging the same outwardly of said bore, whereby upon sufilcientwear of said lining said piston will engage s'aid drum on movement ofthe shoe towards said drum.

EDWARD A. BRANSCHOFSKY.

References Cited in the file of this patent UNI'IED STATES PATENTS NmmirName Date 1,9(121153 Qataudella Mar. 21, 1933 2, 1fl6,57 Schweikle Feb.'7, 1939 2,217,176 Madison Oct. 8, 1940 2,494,269 Sparkes Jan. 10, 1950FoREiGN arrears" Number Gountry Date 118,360 Great Britain Aug. 29, 1918

